Smaller, compact camera designs require compact lens modules. Functions such as zoom and autofocus are also desirable. The camera lenses are often assembled together in a module known as a compact camera module (CCM).
The size of the lens assembly can be reduced by using several smaller lenses rather than fewer large lenses. The lenses may be grouped together into groups of lenses that are moved together as a group relative to the other groups of lenses to achieve the zoom function.
The lens groups are moved along the optical axis to vary the zoom magnification. Typically a small step motor drives a screw rail mechanism to move a lens group for zoom or autofocus functions. The motor may instead drive a gear system that moves groups of lenses. Separate actuators and magnets may be used for the zoom and autofocus functions. The motors are often located at the side of the lenses, offset from the optical axis, but some may place the motors around the optical axis for a more compact design.
While useful, motors and gear or screw mechanisms are relatively bulky and thus increase the size of the compact camera module. A compact camera module is desired that locates the step motor around the optical axis. A compact camera module is desired that shares a magnet for the step motor with both the zoom function and the autofocus function.